The Kaiser Family Foundation has released a brief explaining the national health care reform law's method for calculating income to determine Medicaid eligibility.  The brief explains how the new rules will determine income and also compares them to previous income eligibility calculation methods.

From the report:

To provide individuals and families access to affordable, high-quality health care, the Patient Protection and Affordable Care Act (ACA) expands Medicaid to cover low-income adults and children with incomes up to 133 percent of the poverty line. Millions of low-income parents, non-disabled adults who do not have dependent children (and who are generally ineligible for Medicaid today except in a small number of states) and, in some instances, children now covered through the Children’s Health Insurance Program (CHIP) will become newly eligible for health coverage through Medicaid as a result.

Full report: Explaining Health Reform: The New Rules for Determining Income Under Medicaid in 2014 (PDF | 952.90 KB)

Kaiser Family Foundation.  (2011).  Explaining health reform: the new rules for determining income under Medicaid in 2014.